The chick cardiovascular system will be used to substantiate the possible relationship between hemodynamic alteration and the production of congenital cardiovascular anomalies. Sympathomimetic amines -- with and without adrenergic blocking agents -- will be administered to chick embryos at a stage of embryogenesis which has proven to be most sensitive to these compounds. Blood flow changes in the aortic arch system of embryos will be recorded on movie film which will be filed for subsequent data correlation. Also, specific beta-1 and beta-2 adrenoreceptor stimulants and blocking agents will be tested in this system. In this manner an attempt will be made to amplify the relationship between stimulated beta adrenoreceptors in the chick cardiovascular system and the development of cardiovascular anomalies. Heart rate and blood pressure will be measured in five day old chick embryos which have been exposed to substances capable of inducing aortic arch and cardiac malformations. If hemodynamic effects result from beta adrenoreceptor stimulation and appear to be related to cardiovascular anomalies produced, attempts will be made to reproduce those effects in embryonic chicks with other compounds. BIBLIOGRAPHIC REFERENCES: Hodach, R.J., Hodach, A.E., Fallon, J.F., Folts, J.D., Bruyere, H.J. and E.F. Gilbert: The Role of Beta-Adrenergic Activity in the Production of Cardiac and Aortic Arch Anomalies in Chick Embryos. Teretology 12:33-46, 1975. Gilbert, E.F., Hodach, R.J., Bruyere, H.J. and M.O. Cheung: The Effect of Practolol on Aortic Arch Malformation in Beta-Adrenoreceptor Stimulated Chick Embryos, abst. Teratology, April 1976. In press.